I have a rotating chicken garden / run set up here is the thread I started it has some pics
http://www.theeasygarden.com/forum/viewtopic.php?id=31215
I have anywhere from 9 to 15 chickens in each garden/coop right now 9 in each. I haven't kept up w/ this thread like I should, when I have more time later today or this week I'll probably update it.
Eating the green stuff and bugs is one thing they will do very well at that, but I have runner grass and lots of it, they don't kill it out by any stretch of the imagination. They will eat most of the green out, but you are still left w/ digging out the roots. This is my second year into this style of gardening I have had successes and failures, also if I were starting over there are some changes I would make to my system, fewer individual gardens to rotate through, and a built in moat w/ each coop / garden is one huge change I would make.
Before I started this I kept hearing how great of "tillers" the chickens were and how much they would dig up the garden / yard, trust me when I say that is waaaaaaaaaaaaaay overstated. They are awesome at what they do, and can add a lot to a garden system, but if you have a perfectly tilled garden spot in your imagination, it isn't going to happen. They will eat out most of the green, and a lot of the bugs, they will dig a couple of chicken sized divets in the ground for dust bathing, and if you go in and dig w/ a shovel they will gladly snatch any and all bugs you displace, but you will have to remove the grass roots and if you leave a sod of dirt/grass overturned thinking they will dig through it removing the dirt in a hunt for ground insects, they won't, your overturned clumps of dirt and root will be left untouched.
I'm unsure about what specific info you are looking for, but if you have any specific questions I will do my best to answer based on my experience w/ this so far.
It takes my 9 chickens a couple of weeks to clean out all or most of the vegetation in a 20 x 20 x 3 foot garden (some green they never eat)